Power actuated handheld tensioning and cutoff tool

Abstract

A power assisted system for tensioning and cutting off flexible cable ties includes a handheld unit coupled to a remote power unit by a flexible pull-cable. A trigger on the handheld unit signals the remote power unit to pull the pull-cable and thereby actuate the tool. A tie gripping and tensioning mechanism is provided in the handheld unit as is a cutoff mechanism that automatically cuts off the cable tie tail when the desired tension is achieved. Because operating power is provided by the remote unit, the handheld unit can be made small and lightweight without sacrificing power. Control signals are communicated from the handheld unit to the remote unit through wires carried alongside the pull-cable within a common sheath. Alternatively, the control signals can be communicated through the pull-cable itself.

We claim: 
     
       1. A power assisted tensioning and cutoff tool system comprising: a remote power unit;   a handheld unit operable to tension a cable tie and to cutoff the excess portion of the cable tie when a predetermined tension has been achieved in the cable tie;   a power transfer member interconnecting the remote power unit with the handheld unit for transferring actuating power from the remote power unit to the handheld unit; and   a user actuatable trigger for actuating the remote power unit to transfer actuating power to the handheld unit.   
     
     
       2. A power assisted tensioning and cutoff tool system as defined in claim 1 wherein the handheld unit comprises a pistol-like member. 
     
     
       3. A power assisted tensioning and cutoff tool system as defined in claim 1 wherein the power transfer member comprises an elongate flexible cable. 
     
     
       4. A power assisted tensioning and cut-off tool system as defined in claim 3 wherein the elongate flexible cable includes a pull-cable. 
     
     
       5. A power assisted tensioning and cutoff tool system as defined in claim 4 wherein the remote power unit actuates the handheld unit by pulling the pull-cable. 
     
     
       6. A power assisted tensioning and cutoff tool system as defined in claim 1 wherein the user-actuatable trigger comprises a push-button on the handheld unit. 
     
     
       7. A power assisted tensioning and cutoff tool system as defined in claim 1 wherein the remote power unit includes a linear actuator actuated in response to actuation of the pushbutton. 
     
     
       8. A power assisted tensioning and cutoff tool system as defined in claim 7 wherein the handheld unit includes a gripping and tensioning mechanism operable to grip and pull the tail of the cable tie to thereby tension the cable tie. 
     
     
       9. A power assisted tensioning and cutoff tool system as defined in claim 8 wherein the gripping and tensioning mechanism is linearly reciprocable in the handheld unit. 
     
     
       10. A power assisted tensioning and cutoff tool system as defined in claim 9 wherein the gripping and tensioning mechanism linearly reciprocates between an initial position and a final position and wherein the handheld unit further includes a sensor for sensing when the gripping and tensioning mechanism is near the final position. 
     
     
       11. A power assisted tensioning and cutoff tool system as defined in claim 10 wherein the remote unit is operable to reciprocate the gripping and tensioning mechanism from the final position to the initial position when the sensor senses that the gripping and tensioning mechanism is near the final position. 
     
     
       12. A power assisted tensioning and cutoff tool system as defined in claim 11 wherein the sensor and the pushbutton communicate with the remote power unit through the elongate flexible cable. 
     
     
       13. A power assisted tensioning and cutoff tool system as defined in claim 12 wherein the sensor and the pushbutton communicate electrically with the remote power unit and wherein the elongate flexible cable includes wires for communicating the sensor and the pushbutton with the remote power unit. 
     
     
       14. A power assisted tensioning and cutoff tool system as defined in claim 12 wherein the sensor and the pushbutton communicate electrically with the remote power unit and wherein the sensor and the pushbutton communicate electrically with the remote power unit through the pull-cable. 
     
     
       15. A power actuatable handheld tool for tensioning a cable tie and for cutting off the tie tail portion of the tensioned cable tie comprising: a pistol-shaped housing having a handle portion and a barrel portion;   a trigger link within the handle portion movable between an initial position and a final position;   a tie gripping and tensioning mechanism in the barrel portion and coupled to the trigger link for gripping the tie tail of the cable tie and pulling the tie tail in response to movement of the trigger link from the initial position to the final position;   a cutoff mechanism coupled to the trigger link for severing the tie tail when tension in the tie tail reaches a predetermined threshold: and   structure for connecting the trigger link to an external source of actuating power.   
     
     
       16. A power actuatable handheld tool as defined in claim 15 wherein the structure comprises a connection for attachment to the end of a linearly movable pull-cable. 
     
     
       17. A power actuatable handheld tool as defined in claim 16 wherein the structure further includes a clamp for securing to an outer sheath surrounding the pull-cable. 
     
     
       18. A power actuatable handheld tool as defined in claim 17 wherein the trigger link comprises an elongate member having an upper end pivotably coupled to the barrel portion of the housing and a lower end adjacent the lower end of the handle portion. 
     
     
       19. A power actuatable handheld tool as defined in claim 18 wherein the connection pivotally joins the end of the pull-cable to the lower end of the trigger link. 
     
     
       20. A power actuatable handheld tool as defined in claim 19 wherein the clamp is located adjacent the lower end of the handle portion. 
     
     
       21. A power actuatable handheld tool as defined in claim 15 further comprising a user-actuatable input for controllably actuating the handheld tool. 
     
     
       22. A power actuatable handheld tool as defined in claim 21 wherein the user-actuatable input comprises a push button. 
     
     
       23. A power actuatable handheld tool as defined in claim 22 further comprising a first communications link for communicating the push button with the external source of actuating power. 
     
     
       24. A power actuatable handheld tool as defined in claim 23 wherein the first communications link communicates electrically with the external source of actuating power. 
     
     
       25. A power actuatable handheld tool as defined in claim 24 further comprising a sensor for sensing when the trigger link is adjacent the final position. 
     
     
       26. A power actuatable handheld tool as defined in claim 25 further comprising a second communications link for communicating the sensor with the external source of actuating power. 
     
     
       27. A power actuatable handheld tool as defined in claim 26 wherein the second communications link communicates electrically with the external source of actuating power. 
     
     
       28. A power actuatable handheld tool as defined in claim 27 wherein the first and second communications links comprise a plurality of wires coupled between the push button and the external source of actuating power and between the sensor and the source of actuating power. 
     
     
       29. A power actuatable handheld tool as defined in claim 27 wherein actuating power is delivered to the trigger link by means of a pull-cable and wherein the first and second communications links transmit control signals along the pull-cable. 
     
     
       30. A remote power unit for supplying actuating power to a handheld tool operable to tension a cable tie and to sever the tie tail of the tensioned cable tie comprising: a linear actuator;   a pull-cable coupled to the linear actuator; and   a control system responsive to first and second control signals developed by the handheld tool, the control system being operable to actuate the linear actuator to pull the pull-cable from an initial position to a final position in response to receipt of the first control signal and to return the pull-cable from the final position to the initial position in response to receipt of the second control signal.   
     
     
       31. A remote power unit as defined in claim 30 wherein the control system includes a plurality of conductors for communicating the first and second control signals from the handheld tool to the remote power unit. 
     
     
       32. A remote power unit as defined in claim 31 wherein the plurality of conductors and the pull-cable are together housed within a single flexible sheath. 
     
     
       33. A remote power unit as defined in claim 30 wherein the control system receives the first and second control signals from the handheld tool through the pull-cable. 
     
     
       34. A remote power unit as defined in claim 30 wherein the linear actuator includes a threaded shaft and a nut assembly linearly movable along the threaded shaft in response to rotation of the threaded shaft. 
     
     
       35. A remote power unit as defined in claim 34 wherein the pull-cable is coupled to the nut assembly and the rotatable shaft is turned by means of an electric motor. 
     
     
       36. A remote power unit as defined in claim 35 wherein the control system is operable to turn the electric motor in either direction to thereby move the nut assembly in either direction along the threaded shaft and thereby move the pull-cable between the initial and final positions. 
     
     
       37. A remote power unit as defined in claim 36 wherein the control system operates to turn the electric motor in a first direction in response to the first control signal and to turn the electric motor in the opposite direction in response to the second control signal. 
     
     
       38. A remote power unit as defined in claim 37 wherein the control system includes a limit switch that is actuated by the nut assembly when the pull-cable is in the initial position. 
     
     
       39. A remote power unit as defined in claim 37 wherein actuation of the limit switch signals the control system to stop turning the electric motor in the opposite direction. 
     
     
       40. A power actuatable handheld tool for tensioning a cable tie and for cutting off the tie tail portion of the tensioned cable tie comprising: a pistol-shaped housing having a handle portion and a barrel portion;   a trigger link within the handle portion movable between an initial position and a final position;   a tie gripping and tensioning mechanism in the barrel portion and coupled to the trigger link for gripping the tie tail of the cable tie and pulling the tie tail in response to movement of the trigger link from the initial position to the final position;   a cutoff mechanism coupled to the trigger link for severing the tie tail when tension in the tie tail reaches a predetermined threshold;   a pull-cable connected to the trigger link and operable to pull the trigger link from the initial position to the final position; and   a return mechanism for returning the trigger link from the final position to the initial position when the pull-cable ceases pulling the trigger link toward the final position.   
     
     
       41. A power actuatable handheld tool as defined in claim 40 wherein the cutoff mechanism includes a cutoff cam and wherein the trigger link is coupled to the cutoff mechanism through an actuating link having one end coupled to the trigger link and another end coupled to the cutoff cam. 
     
     
       42. A power actuatable handheld tool as defined in claim 41 wherein the trigger link is coupled to the tie gripping and tensioning mechanism through a short link having one end coupled to the actuating link and another end coupled to the tie gripping and tensioning member. 
     
     
       43. A power actuatable handheld tool as defined in claim 42 wherein the other end of the short link is coupled to the tie gripping and tensioning member through a handle link. 
     
     
       44. A power actuatable handheld tool as defined in claim 43 wherein the return mechanism comprises a return spring engaging the handle link. 
     
     
       45. A power actuatable handheld tool as defined in claim 44 wherein the short link, the handle link and the return spring are all disposed within the handle portion. 
     
     
       46. A power actuatable handheld tool as defined in claim 45 wherein one end of the handle link is pivotally coupled to the housing, the other end of the handle link is coupled to the tie gripping and tensioning member and the short link is pivotally coupled to the handle link between the ends of the handle link. 
     
     
       47. A power actuatable handheld tool as defined in claim 46 wherein the handle portion includes a front side and a backside and wherein the trigger link extends within the handle portion for pivotable movement from the initial position along the front side of the handle portion to the final position adjacent the backside of the handle portion. 
     
     
       48. A power actuatable handheld tool as defined in claim 47 wherein the trigger link includes a lower end and the pull-cable is coupled to the lower end of the trigger link. 
     
     
       49. A power actuatable handheld tool as defined in claim 48 wherein the handheld tool further includes a pushbutton actuating switch extending forwardly from the front side of the handle portion. 
     
     
       50. A power actuatable handheld tool as defined in claim 49 wherein the handheld tool further includes a proximity switch within the handle portion adjacent the backside of the handle portion for sensing when the trigger link is in the final position adjacent the backside of the handel portion. 
     
     
       51. A power actuatable handheld tool as defined in claim 50 wherein the pull-cable is enclosed within an outer sheath and the handheld tool further includes structure for securing the outer sheath to the handle portion. 
     
     
       52. A power actuatable handheld tool as defined in claim 51 wherein the structure is disposed adjacent the lowermost end of the handle portion.